io6 
SCIENCE. 
spectra of CC 1 4 , CioHe, CN, CHI,, CS,, CO,, CO, &c„ 
have been mapped, and both the common and special lines 
and flutings thus determined. 
The phenomena seen with more or less constancy are a 
blue line, with a wave-length of 4266 ; a set of blue tim- 
ings, extending from 4215 to 4151 ; and another set of ultra- 
violet flutings, which extend from 3885 to 3843 (all approx- 
imate numbers). 
In a photograph of the spectrum of the electric arc 
the spectrum which contains the blue line alone and that 
which contains the blue fluting alone (Fig. 4). In compar- 
ing the spectra of carbon under different conditions, I find 
this to be true. The blue line never appears in conjunction 
•with the blue Jlutings , unless the ultra-violet /lutings are also 
present. In other words, the highest and the lowest hypo- 
thetical temperature spectra are never visible together with- 
out the spectrum of the intermediate hypothetical temper- 
ature. 
Highest temperature. 
Intermediate. 
Lowest temperature. 
Fig. 3 — Action of three different temperatures on a hypothetical substance, assuming three stage of complete dissociation. 
(with a weak battery) between carbon poles in an atmos- But this is not all. By placing the spectra of the sub- 
phereof chlorine, the blue flutings alone are visible, whilst, stances at different heat-levels, so to speak, I was enabled 
when the spark is similarly photographed, the ultra-violet to construct a map, which not only indicates the mere pres- 
flutings and the blue line (4266) are also visible, whilst ence or absence of , the lines and their relative intensities, 
the blue flutings becorrle fainter. but shows a perfect gradation between the spectrum which 
From this we may assume, in accordance with tha contains the line alone and that which contains the blue 
working hypothesis of a series of different temperature flutings alone (Fig. 5). I would point out that there is noth- 
furnace*, as set forth in the paper of December, 1878 (see ing theoretical in this map. All the horizons depicted are 
Furnace A 
Inter- ( 1 
mediate. ( 2 
Furnace B 
Inter- ( 1 
mediate. ( 2 
Furnace C 
Highest temperature. 
Lowest temperature. 
Fig. 4 — Spectra of the hypothetical substance, in intermediate furnaces, assuming that the vapours are not completely dissociated. 
Fig. 3), that the different flutings and the line correspond 
to different temperature spectra, the blue flutings to the 
lowest and the blue line to the highest temperature, whilst 
the ultra-violet flutings occupy an intermediate position. 
According to this working hypothesis there should be 
copied from photographs of carbon under the conditions in- 
dicated, and theory has merely enabled me to arrange them 
in order. 
This map I submit, therefore, bears out the hypothesis of 
differences of temperature indicated above, for it is seen 
Highest temperature. 
Lowest temperature. 
Fig. 5 — The photographed spectra of some carbon compounds. 
Spark in Ci 0 H 8 and CH 1 3 
Spark CO 
“ CO, 
“ CN. 
“ CS. 
Arc in Cl (B). 
“ Cl (C). 
a series of horizons forming a perfect gradation between I flutings appear first and grow in intensity. As these in- 
that, while the blue line gradually thins out, the ultra-violet creasethe blue flutings become visible, and further, as the 
